Local Augmentation to Wide Area PPP Systems A Case Study in - - PowerPoint PPT Presentation

Local Augmentation to Wide Area PPP Systems

A Case Study in Victoria, Australia

Ken Harima*, Suelynn Choy*, Luis Elneser** and Kazutoshi Sato*** * School of Science, RMIT University, Australia ** Position Partners, Australia ***Japan Aerospace Exploration Agency (JAXA), Japan

Outline

• 1. PPP as a wide area positioning technique
• 2. PPP-RTK: augmented PPP with local corrections
• 3. Case study in Victoria: slant ionosphere generation
• 4. Case study in Victoria: PPP-RTK positioning
• 5. Summary

2 December 2016 IGNSS 2016, Sydney Australia

Precise Positioning: PPP and RTK

PPP

• Light infrastructure

requirements

• Relative low data rate

requirements

• Sub-decimetre steady state

accuracy

• Tens of minutes of

convergence time

• Suitable for wide area

infrastructure RTK

• Relatively dense CORS

network required

• Interactive or high data rate

communication system required

• Centimetre level accuracy
• Rapid to instantaneous

convergence

• Optimal for regions with

dense CORS and communication networks

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PPP: MADOCA and CLK91 Corrections

• Global real-time PPP streams are

available from multiple sources

• CLK91

– GPS & GLO – Satellite orbits, clocks and signal biases – Available through IGS NTRIP caster

• MADOCA:

– GPS, GLO & QZSS – Satellite orbits, clocks and estimated URA – Signal bias in development – Undergoing broadcast tests by QZSS LEX signal

December 2016 IGNSS 2016, Sydney Australia 4

QZSS LEX coverage area

PPP-RTK: Concept

• Challenge: precise ionospheric corrections are required for rapid

convergence

• Global precise ionospheric delay estimations for PPP-RTK are not yet

available

• They are impractical for satellite transmission for nationwide coverage
• PPP-RTK: Using CORS networks to generate a local augmentation to

global PPP products:

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–RTK-like performance inside or near network –PPP performance over wide area coverage –Seamless transition between PPP and RTK mode

PPP-RTK concept

PPP-RTK: GNSS Corrections and PPP Modes

• PPP: Precise satellite orbits and clocks allows to calculate float

ambiguities

• PPP-AR: Signal biases allows for isolation and resolution of

ambiguities

• PPP-RTK: Ambiguity convergence can be assisted by ionospheric

corrections

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∆𝑀𝑗𝑗 + 𝑑∆𝒆𝒆𝑻 + ∆𝒄𝒋𝒋 = ∆𝜍 + λ𝑂𝑂∆𝑂1 − 𝐷2λ2 ∆𝑂1 − ∆𝑂2 ∆𝑄

𝑛𝑛 + ∆𝑪𝒏𝒏 = λ𝑋𝑂 ∆𝑂1 − ∆𝑂2

∆𝑀𝑕𝑗 + ∆𝒄𝒉𝒋 − 1

𝐷2𝑱 = λ1 − λ2 ∆𝑂1 + λ2 ∆𝑂1 − ∆𝑂2

∆𝑀𝑗𝑗 + 𝑑∆𝒆𝒆𝑻 = ∆𝜍 + λ𝑂𝑂∆𝑂1 − 𝐷2λ2 ∆𝑂1 − ∆𝑂2 − ∆𝑐𝑗𝑗

PPP-RTK: Single Base Station Example

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MOBS (base) DORA (rover) 17 Km

Single base PPP-RTK test on 7th July 2016

Case Study in Victoria: Generation of Ionosphere

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Inter-station spacing ≈ 60 km Reference station Monitoring station

Small network PPP-RTK test in August-September 2016

Case Study in Victoria: Accuracy of Ionosphere

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• Interpolated vs measured Ionosphere, 31st August to 5th September 2016
• RMS: 2.6 cm (CLK91); 3.2 cm (MADOCA)
• CLK91 (red)
• MADOCA (blue)

Case Study in Victoria: Transmission of Corrections

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Constellation Orbit (s) Clock (s) Code Bias (s) Phase Bias (s) Ionosphere (s) GPS 30 5 30 30 30 or 5 GLONASS 30 5. 30 30

• Local enhancement delivery modes: satellite delivery and mixed delivery

Case Study in Victoria: PPP-RTK Results (CLK91)

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PPP-AR (red) and PPP-RTK (blue) solutions convergence times to within < 10 cm using CLK91 corrections.

Case Study in Victoria: PPP-RTK Results (MADOCA)

December 2016 IGNSS 2016, Sydney Australia 12

PPP-AR (red) and PPP-RTK (blue) solutions convergence times to within < 10 cm using MADOCA corrections.

Case Study in Victoria: La Trobe Valley Coal Mine

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Case Study in Victoria: Dynamic Tractor Results

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Accuracy of MADOCA (blue) and CLK91 (cyan/green) based PPP-RTK solutions. Yallourn 1st September 2016

Summary

• PPP provides wide area coverage with sparse CORS network.
• RTK provides fast convergence to centimetre level positioning accuracy, but

has high dependency on the density of CORS network.

• PPP-RTK is a synthesis of the positive characteristics of PPP and network-

RTK

• The computed ionopheric corrections have an estimated accuracy of 3 cm or

better.

• PPP-RTK kinematic processing on fixed stations:

– 40% reduction in horizontal RMS – 40% reduction in vertical RMS in the first 30 minutes – 67% of solutions converge to 10 cm horizontal accuracy in 16 minutes (compared to 75 minutes without ionospheric corrections)

• Future work: ionosphere mapping for wider areas, tropospheric corrections.

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Acknowledgements

• Cooperative Research Centre for Spatial Information (CRCSI), Australia
• RMIT University, Australia
• Geoscience Australia (GA)
• Land Information New Zealand (LINZ)
• Department of Environment, Land, Water and Planning (DELWP)
• Position Partners Pty Ltd
• Fugro Satellite Positioning Pty Ltd
• Japan Aerospace Exploration Agency (JAXA), Japan
• French Government Space Agency (CNES), France

* Disclaimer: Any opinions expressed in this presentation are solely the second author’s and do not necessarily represent those of these organisations listed herein.

December 2016

Thank you

16

IGNSS 2016, Sydney Australia